The crystal state of a compound may be important when the compound is used for pharmaceutical purposes. Compared with an amorphous solid, the solid physical properties of a crystalline compound may change from one solid form to another, which may affect its suitability for pharmaceutical use. In addition, different solid forms of a crystalline compound can incorporate different types and/or different amounts of impurities. Different solid forms of a compound can also have different chemical stability upon exposure to heat and/or water over a period of time.
Ceftolozane is a cephalosporin antibacterial agent, also referred to as CXA-101, FR264205, or by chemical names such as (6R,7R)-3-[(5-amino-4-{[(2-aminoethyl)carbamoyl]amino}-1-methyl-1H-pyrazol-2-ium-2-yl)methyl]-7-({(2Z)-2-(5-amino-1,2,4-thiadiazol-3-yl)-2-[(1-carboxy-1-methylethoxy)imino]acetyl}amino)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, and 7β-[(Z)-2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(1-carboxy-1-methylethoxyimino)acetamido]-3-{3-amino-4-[3-(2-aminoethyl)ureido]-2-methyl-1-pyrazolio}methyl-3-cephem-4-carboxylate. Ceftolozane sulfate is a pharmaceutically acceptable ceftolozane salt of formula (I) that can be formulated for intravenous administration or infusion.

U.S. Pat. No. 7,129,232 discloses ceftolozane hydrogen sulfate salt among other salts “with a base or an acid addition salt such as a salt with an inorganic base, for example, an alkali metal salt [e.g., sodium salt, potassium salt, etc.], an alkaline earth metal salt [e.g., calcium salt, magnesium salt, etc.], an ammonium salt; a salt with an organic base, for example, an organic amine salt [e.g., trimethylamine salt, triethylamine salt, pyridine salt, picoline salt, ethanolamine salt, triethanolamine salt, dicyclohexylamine salt, N,N′-dibenzylethylenediamine salt, etc.]; an inorganic acid addition salt [e.g., hydrochloride, hydrobromide, sulfate, hydrogen sulfate, phosphate, etc.]; an organic carboxylic or sulfonic acid addition salt [e.g., formate, acetate, trifluoroacetate, maleate, tartrate, citrate, fumarate, methanesulfonate, benzenesulfonate, toluenesulfonate, etc.]; and a salt with a basic or acidic amino acid [e.g., arginine, aspartic acid, glutamic acid, etc.].” In addition, U.S. Pat. No. 7,129,232 discloses a crystal solid form of ceftolozane sulfate obtained by dissolving ceftolozane sulfate in a solution of water and ethanol, adding seed crystals, to obtain the crystal form described herein as (Comparative) Example 1. A synthesis of ceftolozane is also described in U.S. Pat. No. 7,129,232.
As reported herein, there remains a need for solid forms of ceftolozane having improved ceftolozane stability. For example, the purity of ceftolozane in an aqueous ethanol solution during precipitation according to the methods of U.S. Pat. No. 7,129,232 decreased from about 97% to about 68% during a 6-day stability test (See Example 3), as measured by high performance liquid chromatography (HPLC). Accordingly, there remains a need for solid forms of ceftolozane greater ceftolozane stability for use in drug substance and drug product development.